[133.01] Stars, Gas, and Dust in the Universe

D. Calzetti (Space Telescope Science Institute)

The interplay between stars, gas, and dust determines the
spectral energy distribution (SED) of non-active galaxies
and, ultimately, the observable quantities at any
wavelength. Such observables have a profound impact on our
understanding of how galaxies evolve, as they represent our
probes into the Universe. The age distribution of the stars,
the intensity and distribution of the recent star formation,
and the content and distribution of dust in the galaxy
provide the bulk SED properties. Far from being a secondary
`ingredient', dust contributes one-half or more of the
energy budget in galaxies at all redshifts. I review recent
progress in our knowledge of the star formation and of the
dust content of galaxies in the local Universe, and of their
evolution as a function of cosmic time. I discuss how global
galactic parameters (morphology, luminosity, and activity
level) are linked to the dust content and opacity of
galaxies. Much of what we do not know about dust and star
formation is related to limitations in our observational
capabilities, either in the multi-wavelength range or in the
angular scales probed. For instance, the physical
relationship between the stellar populations and the various
dust emission components in galaxies has so far remained
uncharted because of the spatial resolution mismatch between
optical and far-infrared telescopes. I highlight how
upcoming facilities in the near future (e.g., SIRTF) can
shed light on a number of such open issues.